1. Field of the Invention
This invention relates generally to the method and system of testing the integrated circuits (ICs) and printed circuit board (PCB). More particularly, this invention relates to an electromechanically driven test head with miniaturized physical size with pin electronics in the test head such that the signal path from the pin electronics to the device under test (DUT) is less than ¼ wavelength of the highest frequency component of the driving signal.
2. Description of the Prior Art
As the integrated circuits (ICs) and electronic components supported on a printed circuit board (PCB) become more complicate with higher level of integration and increasingly faster operational speed, the test heads implemented in conventional techniques of IC and PCB circuit testing are challenged by many technical difficulties. One particular difficulty is the large size of the test heads due to the use of relay to switch off and isolate the high speed pin electronics from the low speed parametric and analog test circuitry so that the high speed signal from the pin electronics will not be effected during high speed testing. The physical size and the parasitic capacitance of the relays thus become the major obstacle to the miniaturization of the test head.
The difficulty becomes even more pronounced now due to the increase of operational speed and pin count of an IC test system. In the conventional the IC test system design, the pin electronic signal driving and receiving path to the device under test is required to be a 50 ohm transmission line with matching termination impedance to avoid a problem of signal reflection when the length of the drive path exceeds ¼ wavelength of the driving and receiving signal. Due to the large size of the relays used in the conventional test head, the transmission line requirement for the IC test system's pin electronic presents a very difficult task for IC test system test head design and down grade the tester performance especially for DUT which has no transmission line driving capability In order to reduce the cost of IC testing operations and to increase the performance of the IC test systems there are ever-increased demand to miniaturize the test head to eliminate the transmission line requirement.
Therefore, a demand still exists in the art of IC testing to provide a new configuration and method to reduce the size of the test head such that the above-mentioned difficulties can be resolved.